Art of producing hollow castings



A. H. EMERY. ART OF PRODUCING HOLLOW CASTINGS- Patentd Sept- 27,1921.

1 i! I I n a l a "\L. V v x i the process may be carried out UNITED STATES PATENT OFFICE.

ALBERT H. EMERY, OF STAMFORD, CONNECTICUT.

ART OF PRODUCING HOLLOW CASTINGiS.

- Application filed May 12,

To all whom it may concern:

Be it known that I, ALBERT H. EMERY, a citizen of the I'nited States, residing at Stamford, in the county of Fairfield and State of Connecticut, have invented certain new and useful Improvements in the Art of Producing Hollow Castings, of which the following is a specification.

My invention relates to a method of form in a hollow casting and cooling it very qulckly in a manner to avoid segregation to cause large initial cooling strains of compression at the bore and tension at the exterior of the casting, and is especially applicable in the manufacture of castings which subsequently form guns or parts of guns. The'present invention may be applied with especial advantage in the production of hollow bodies that are to be used in. constructing guns in accordance with one oranother of my methods of radlal hydraulip straining.

My invention is illustrated in the accompanying drawings, in which- Figure 1 shows a vertical longitudinal section ofa mold, a casting therein, and a means of applying acooling medium to the interior of the casting; and

' Fig. 2 is a transverse section on the line '2" x of Fig. 1 through the centering block or step for the cooling core.

Referring to the drawings in detail, 1 is an ingot mold of circular cross section with its interior made closely to the form the finished product is to have. 2 represents a casting poured into said mold as a step in the process to which the present invention relates. 3 is a thinwalled hollow cylinder or core forming the bore of the casting. 4 is a head for carrying the core 3. 5 is a perforated pipe for introducing a cooling medium into the hollow core. 6 is a block of refractorymaterial located at the bottom of the casting and having a conical opening for centering the core 3 therein. It is provided with longitudinal ribs 6, referably three in number, on its conical ace, as shown in Fig. 2, leaving intervening grooves 6 through which molten metal may escape when the'core 3 is forced downward to its seat.

-With the apparatus as above described, as follows The quantity of metal necessa to make a a casting is determined, and t en a quan- Specification of Letters Patent. Pate t d S t 27 1 21 1920. Serial No. 380,743.

tity of molten metal slightlyin excess of this is introduced into the mold. The mass of metal be1n large and of considerable diameter relative to its length, the impuriit, and the excess meta to overflow. As the core is smooth and the metal still liquid, its insertion will not churn up the metal and' the lmpurities at the top will rise with the liquid and flow off with the excess metal. The form of the molten mass is greatly changed by the introduction of this core, and now its thickness is small relative to its length and this thin wall chills very quickly reducing segregation. and as it is largely cooled from the interior'it will have large inltial strains of compression in the interior and tension on the exterior as is desired. This core 3 is made of a thin wall of steel or iron, and remains in the casting and is bored out 1n machlnmg.

Water or some other cooling agent is introduced into the core 3 as the core is forced down into the mold, to keep the core from be ing overheated and losing its strength, and this supply of cooling medium is continued in sufficient quantity to cause the interior of the casting to cool rapidly. To carry down the core 3 and pipe 5, the mold will be asso-- ciated with suitable means, such as by locating it beneath the ram of a hydraulic, pneumatic, or dead weight ress. There will also be provided an exit or the cooling medium. v V

The pipe 5 .is best made with a series of radial holes along the portion that enters, within 'the' core, so that the cooling medium can be sprayed against the walls of the core.

The lowerend of core 3 is made conical so as to be held central by entering the conical recess in the lower part of the mold.

The effects of this method of casting are three fold. First, it makes it possible to eject some of the impurities from the mold and to cool the remaining metal very rapidly and so reduce the amount of se ation and the amount of sink head requlre sec.-

. 0nd,.this rapid cooling greatly increases the strength of the metal; and, third, by cooling fromthe interior, the metal near the center will solidify and cool first, and then as the metal outside of this solidifies and cools it will contract onto the metal already solidi- ,ified and put the latter under large initial strains of compression, which is desirable in castings-for guns.or parts thereof.

' turned and bored, and then cold forged or It will be advantageous to preheat the mold so that the exterior will not chill prematurely. Y

After cooling, the casting should be rough expanded by the use of internal hydraulic pressure as described and claimed in m atents Nos. 726,520 of April 28, 1903, and

727,766 of May 12, 1903, according to whichguns are constructed with permanent strains of tension on the exterior and compression on the interior by slowly and permanently expanding, from the interior outward, the interior and exterior parts of the gun, or of two or more concentric pieces which are to be as- I sembled in'building up a gun this expanding working, using three or more packings around the straining bar to form two or more chambers, and introducing different degrees of hydraulic pressure into the respective chambers.

This cold forging will increase the elastic limit of the metal and also its ultimate strength, and increase the initial strains in the castings and bring the casting more exactly and uniformly into the condition of strain desired.

I claim:

1. The manufacture of hollow castings having initial strains of compression at and near the bore by filling a mold partly. full of molten metal and after pouring the metal 7 core cool and thereby cooling the casting principally from its interior.

7 3. The improvement in the art of manufacturing guns, which consists in pouring the metal of the bod or of a body member of the gun into a. mo d, introducing into the metal a hollow core provided with means for cooling the core, and cooling the casting from the interior to the exterior, to develop in the castingstrains of compression on the interibr and of tension on the exterior.

4. The art of casting gun bodies or members ofgun bodies, which consists in molding the casting in hollow cylindrical form and applying a cooling medium to the interior of the casting until the casting is set With strains of compression on its interior and of tension on its exterior.

Si ncd at Glenbrook, Conn., this 8th day of h ay, 1-920.

ALBERT H. EMERY. 

